Guest Columnist: Frédéric BROUARD

Some new interresting points about trees and CTE in SQL Server : transforming a tree from auto reference to interval model (nested sets), calculating levels in interval model, creating a view of auto ref from an interval model, hierarchical numbering of items, and more. This article includes more examples based on his previous work.
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How many of you have written resursive queries in SQL? Or any language since school for that matter? Not many people write recusrive queries because of the complexity, the difficulty to understand how they work, and the chance for heap overflows. However, SQL Server 2005 implements Common Table Expressions and recursion in a way that is much easier to code and incorporates some safeguards. New author SQL Server MVP Frederic Brouard has written a fantastic article looking at resursive queries.
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